Preventing Diabetic Foot Ulcers: A 4-Pronged Approach

ABSTRACT: In the first part of this article (November 2013), we discussed the various precursors and risk factors for diabetic foot ulcers (DFUs)—including joint contractures, arthridities, and callus formation, to name a few. In this article, we will summarize a 4-prong approach to preventing DFUs.
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The adage “an ounce of prevention is worth a pound of cure” is particularly appropriate when talking about prevention of DFUs. Although the majority of DFUs will eventually heal with off-loading and appropriate wound care, the real measures of successful outcomes are durability and restoration of function. A 4-pronged approach including patient education, foot skin and toenail care, appropriate footwear selection, and proactive surgical interventions are the essential measures for prevention of new and recurrent DFUs (Figure 1). In our experiences with healed DFU, lower limb amputations proximal to the midfoot/hindfoot level have only been required in 5 specific situations: 

Figure 1. There are 4 essentials for preventing DFU. When fully implemented almost all new and recurrent foot wounds in patients with diabetes mellitus can be prevented. Prevention starts with patient education, an important role of the PCP. Foot skin & toenail care and protective footwear (yellow boxes) are “defensive” measures that should be done for all patients with DM. When the need arises, proactive surgeries (red box) are indicated and considered an “offensive” measure.

• A new major vaso-occlusive occurrence.

• Patients with uncontrollable deformities of the foot. 

• Intractable pain in the extremity. 

• Patients with pernicious collagen vascular diseases. 

• A subset of patients who have methicillin-resistant Staphylococcus aureus, osteomyelitis, and an apparent immunological deficiency that interferes with the host totally eliminating residual foci of the infection. 

Patient Education

The first step in any preventive care is patient education, and the primary care physician (PCP) role is crucial. All patients with diabetes need a PCP to supervise their medical management and initiate referrals to specialists for selection of higher order protective footwear and surgeries. Essential patient education responsibilities of the primary care physician are 3-fold. 

First, the PCP needs to identify and inform the patient of the risk factors (eg, neuropathy, peripheral artery disease, deformity, previous DFU, and previous amputation) that are antecedents for DFU and the measures that are necessary to mitigate the risk factors. To mitigate the risk factors, patient compliance is required and can be determined by adherence to weight management, blood glucose monitoring, etc (Table 1). Objective parameters can be used to ascertain patient compliance and need to be considered in the context of patients’ goals. A user-friendly, rapidly determined, objective Goal Score is a useful tool to quantify patient’s adherence to medical guidance and how often the patient needs to return for follow-up evaluations to ensure compliance with the PCP’s management (Table 2).  

The second component of patient education to prevent DFU is informing the patient of the “do’s” and “don’ts” of foot health care and wound prevention (Table 3). Common sense “do’s” to prevent DFU include keeping skin of the feet and legs clean and well lubricated, having calluses trimmed by professionals, seeking attention for deformities, and wearing white socks if DFU risk factors are present. Common sense “don’ts” to prevent DFU include walking barefoot, neglecting innocent appearing foot skin wounds, and smoking. Many of the “do’s” and “don’ts” are useful measures for the compliance assessment of the Goal Score.

The third component of the education triad is the selection of appropriate ambulatory activities for the patient at risk for DFU. Optimization of fitness through physical activity must be paired with the selection of ambulatory activities commensurate with the patients’ abilities as well as not putting them at undue risk for developing DFU. A simple to use guideline is a 3-level recommendation that ranges from community to household to non-ambulation (Table 4). Consideration must also be given whether ambulation aids such as canes or wheelchairs are needed and can be designated in association with the level of ambulation. For example, a patient with paraplegia could be a community ambulator with a wheelchair—and even enter into racing events with this aid. 

Foot Skin and Toenail Care

The second strategy for prevention of new and recurrent DFU is the optimization of foot skin health and concomitant toenail management. The skin of patients with diabetes is prone to dryness because of autonomic nervous system dysfunction as well as not fully explainable consequences of diabetes. Other concerns about the vulnerability of foot skin problems in patients with diabetes include loss of elasticity associated with glycosylation, soft tissue atrophy, the propensity to form hypertrophic callus especially at healed wound sites, increased risk for cellulitis, skin fragility, and premature attenuation with repetitive contact pressures over deformities (Figure 2). A unifying factor in these concerns is ischemia to the skin. All of these make the foot skin of the patient with diabetes more vulnerable to DFU.  

Figure 2. This foot of a patient with DM has risks factors (deformity, neuropathy, and peripheral artery disease) for developing a DFU. Skin cleaning and hygiene, plus protective footwear, should be the initial management. If callus and the pre-ulceration worsen under the first metatarsal head, proactive foot surgery should be done starting initially with a tenotomy of the extensor hallucis longus tendon to counteract plantarward pressure on the first metatarsal head, sesamoid complex.

Clean, well-moisturized skin is a fundamental “defense” against skin breakdown that is a precursor to DFU. The benefits of healthy skin are obvious. It remains pliable to better resist repetitive pressure and shear stresses. Clean skin will less likely develop cellulitis, inoculate minor wounds, or develop fungal infections. Assessment and management of the foot skin is easily accomplished with a 3-level grading system (Table 5). This defense measure against DFU is part of the education process for the patient with diabetes and appropriately spearheaded by the PCP.  

Occasionally patchy areas of erythema with or without an eczematous component are noted on the skin of the foot and leg of patients with diabetes. This is indicative of a skin fungal infection with possible allergic component. Consequently, if these skin problems are not recognized and managed appropriately, they may progress to full-blown ulcers. 

Coupled with skin care of the foot is toenail care. The toenails of patients with diabetes are prone to diseases ranging from fungal to dystrophic and from dysmorphic to ingrown. Many of the reasons already noted for the skin being vulnerable to DFU are also the reasons the toenails of patients with diabetes become diseased. Frequently, the diseased toenail is thickened with a honeycomb appearance, ingrown, and dysmorphic (Figure 3). As with the skin, a 3-level assessment system is useful in the evaluation and management of toenail problems in patients with diabetes (Table 5). 

Figure 3. The third and fourth toenails are distorted by fungal and dystrophic changes. Debris is present in the nail folds, a precursor to ingrowth of toenails. The fifth toe nail is dysmorphic with a curvilinear shape. Merely trimming the toenails to the ends of the toes is insufficient management. The thickened toenails need to be debulked and filed to almost tissue paper thinness. The debris in the nail folds requires debridement. The nails should be shortened until the toenail attaches to the underlying nail bed.

Appropriate managed diseased toenails should be debrided to healthy toenail tissue, which may require removing the nail that is unattached to the nail bed to the matrix level. If the toenail remains attached to the nail bed, it should be debulked until tissue paper thinness. Contouring and smoothness can be accomplished with a nail file. After trimming and debridement of diseased toenails, we also “paint” the nails with an iodine solution for disinfection of the nail bed and nail folds (often requiring removal of embedded debris) to prevent infection to the exposed tissue after our aggressive debridements. 

Who should perform the toenail care? When sensory neuropathy is present coupled with diseased toenails, appropriately trained caregivers (ie, podiatrists or other qualified caregivers) should do nail care. With visual impairments, lack of flexibility, obesity or combinations of these, it may be impossible for the patient to do appropriate toenail care. When the patient performs toenail care with these problems, the patient runs the risk of self-inflicted wounds compounded with the use of probable contaminated, non-sterile commercial nail trimmers. These minor wounds in the presence of peripheral arterial disease can rapidly progress to a serious DFU. 

Continued on next page

Protective Footwear

A second defense against the development of DFU is the use of properly selected protective footwear. Two considerations—the severity of the deformity and the number of risk factors present—must be given in selecting protective footwear for patients with diabetes. As each increases, the selection of protective footwear becomes increasingly more sophisticated and costly. Off-loading is the key to managing deformities. However, wedging and arch support may be required when deformities such as hindfoot varus or valgus and midfoot supination or pronation are present. 

Risk factors such as neuropathy, sites of previous wounds, and peripheral artery disease require measures to protect the skin from pressure and shear forces. Off-loading areas of concern is an early intervention to achieve this. Padded inserts, relief of areas of pressure contact (ie, hollowing out the site), and selection of shoes with large toe boxes are some of the initial measures to protect the vulnerable sites from developing DFU.  

A hierarchical approach to the selection of protective footwear should be followed based on the severity of the foot problem (Figure 4). The first level of the hierarchy is the use of quality off-the-shelf athletic or walking shoes. This does not require a prescription nor does Medicare reimburse for the purchase.¹ This level is appropriate for patients without significant risk factors for DFU and minimal loss of sensation in the feet. 

Figure 4. There is a hierarchy of choices for selection of protective footwear. With each level, as one moves upward on the triangle, the choices require more knowledge of the indications, the options and the limitations of the selection (ie, is there a need to move to a higher selection level?). Likewise, the costs approximately double with each level starting with about $150 for quality off-the-shelf walking or athletic shoes.

*CROW = Charcot restraint orthotic walker.

For patients without significant deformities but with sensory neuropathy, off-the-shelf diabetic shoes with extra-depth, padded inserts should be prescribed and is a Medicare Therapeutic Bill benefit.¹ When deformities are present, then custom orthotic, wedges and/or lifts may be required. These may be used in conjunction with ankle-foot orthoses or the double upright (Klenzak) leg brace attached to the shoe to stabilize the foot.  

For severe deformities, such as those associated with Charcot neuroarthropathy, custom-molded shoes or Charcot restraint orthotic walkers (CROW) may be required. With each level of the hierarchy, the cost for the protective footwear approximately doubles starting at about $150 for quality off-the-shelf (non-prescription) shoes. Consequently, due diligence is essential for prescribing appropriate and cost-effective protective footwear. For example, prescribing custom-molded shoes or CROW boots for a bedridden patient is not justifiable. Because of the knowledge needed to prescribe appropriate protective footwear, it should be done by a podiatrist or an orthopedic surgeon who focuses on foot and ankle problems.

In our experiences, about 50% of the prescription protective footwear we prescribe require adjustments, such as relieving pressure contact areas after the initial fitting. Consequently, good communication should be maintained between the prescribing physician and the orthotist/pedorthotist to optimize fitting and protection of the foot with risk factors.

Note: Protective footwear requirements change with time. This is particularly apparent in patients with Charcot neuroarthropathy where deformities often progress with time or new deformities arise. The prescribing physician should be cognizant of this and quickly prescribe adjustments to the protective footwear before DFU develop. This further justifies the need for periodic rechecks of these patients.

Proactive Surgeries

Proactive surgeries are done before DFU develops. It is an offensive tactic that prevents DFU from occurring just as advancing the ball to the goal line helps win the game in football. For the patient with diabetes, “winning the game” is the prevention of a new or recurrent DFU. We have observed that 3 predominant findings are the reason most DFU fail to heal, including the persistence of underlying bony (and/or hypertrophic bursa) deformity, ischemia/hypoxia, and deep unresolved infection. We have coined the term “troublesome triad” for these 3 reasons DFU fail to heal.² The first 2 findings can be managed proactively, that is before a DFU develops from the problem (Table 6). 

Deformities before wounds occur can be managed with surgical techniques. Ischemia/hypoxia can be mitigated with revascularization techniques as well as other interventions such as hyperbaric oxygen treatments, methods to improve blood flow, and edema reduction.³

Many proactive surgeries can be performed in a clinic setting by wound care providers trained in the KISS (Keep It Simple and Speedy) techniques. These include debridement of calluses, percutaneous toe extensor and flexor tenotomies that cause clawing of toes, manipulation of contracted joints, removal of eschars, and debriding fungal-thickened ingrown toenails. 

To perform these procedures in the clinic setting, the care provider must be cognizant of the patient’s sensation at the procedure site. Many patients with diabetes have a severe enough sensory neuropathy that anesthesia is not required. If hypesthesia is present, then field or foot blocks will provide sufficient anesthesia to perform the procedure without discomfort for the patient.

More extensive proactive surgeries are performed in the operating room by surgeons knowledgeable in surgical management of diabetic foot conditions. These procedures include:

• Ostectomy to remove deformities. 

• Alignment corrections with osteotomies plus temporary stabilization with external fixation. 

• Percutaneous Achilles tendon lengthening to address tight heel cords, equinus contractures, and/or deformities that overload the forefoot with weight bearing. 

• Toe or forefoot amputations. 

• Flap or skin graft closures after removing deformities.

• Debridement of bursa and cicatrix (usually over deformities and in conjunction with their removal). 

• Management of forefoot malperforans ulcers under depressed metatarsal heads by scoring the metatarsal neck with multiple drill holes then performing a controlled fracture through the drilled bone to angle the head upward. Many experts recommend total contact casting. While this is an accepted technique, which requires a minimum of biweekly cast changes and as much as 6 months to heal, we have observed healing with the controlled fracture technique usually within a couple of weeks.

Because the deformity is not corrected with total contact casting, 50% recurrence rates have been reported even with post-healing protective footwear.⁴ With the controlled fracture technique, the deformity is corrected and transfer lesions do not occur as observed when the metatarsal head is removed. 

• Obliterating a non-healing forefoot cleft wound with narrowing and temporarily maintaining the position with external fixation. 

Although these surgeries may appear complicated, in reality many are the operating room counterparts of the KISS clinic surgeries. Most are done percutaneously or with limited surgical exposures, as outpatient surgeries and allow immediate full weight-bearing ambulation. 

Prevention of DFU is a crucial goal that every diabetes caregiver should try to achieve. Often the costs of DFU management, especially when it requires hospitalization and surgery, far exceeds all the other costs for managing the patient’s diabetes. Prevention of DFU is a 4-step multidisciplinary process that includes the PCP for education including skin and toenail hygiene, the foot specialist for prescribing protective footwear, debriding diseased toenails, and performing proactive surgeries, and the vascular specialist for revascularizations. Recognition and education about the risk factors for developing DFU that include peripheral artery disease, peripheral neuropathy, deformity, previous diabetic foot wound, and previous amputation is fundamental to all caregivers who manage patients with diabetes. Finally, the PCP should refer their patients with deformities, peripheral artery disease, or both to specialists who can proactively intervene to prevent wound problems. With this approach, almost all DFUs can be prevented. ■ 

References:

1.Janissee DJ. The Therapeutic Shoe Bill: Medicare coverage for prescription footwear for diabetic patients. Foot Ankle Intl. 2005;26(1):42-45.

2.Strauss MB, Miller SS, Aksenov IV. Making the scoring of wounds objective. Wound Care Hyperbaric Med. 2012;3(1):21-37.

3.Strauss MB, Miller SS, Aksenov IV, Manji K. Wound oxygenation and an introduction to hyperbaric oxygen therapy: interventions for the hypoxic/ischemic wound. Wound Care Hyperbaric Med. 2012;3(2):36-51.

4.Frigg A, Pagenstert G, Schafer D, et al. Recurrence and prevention of diabetic foot ulcers after total contact casting. Foot Ankle Int. 2007;28(1):64-69.

Lisa Nhan, DPM, is a third year podiatric surgery and medicine resident with special interest in forefoot reconstructive surgery and diabetic limb salvage at Long Beach Memorial Medical Center, Long Beach, California. She is also a co-investigator on a comprehensive wound scoring research project with Drs Strauss and Miller.

Michael B. Strauss, MD, is an orthopaedic surgeon who focuses on managing limb threatening wounds is the medical director of Hyperbaric Medicine at Long Beach Memorial Medical Center, a clinical professor of orthopaedic surgery at the University of California Irvine and orthopaedic consultant for the Foot & Ankle Clinic at the Veterans Affairs Medical Center, Long Beach, California.

Stuart S. Miller, MD, is the associate medical director of Hyperbaric Medicine at Long Beach Memorial Medical Center, is an emergency medicine physician and has co-authored over 30 articles, book chapters, posters, and a wound care textbook with Dr Strauss.